1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, session_id, ip_address, time_entry, time_last_click, last_page_url) values ('', 'Guest', '8e0bc0188e0d1eaa4a4609f005ebf9ec', '216.73.216.42', '1763466250', '1763466250', '/shop/product_info.php?info=p39_.html')

[XT SQL Error]